This invention relates to a device for monitoring and controlling a fluid product transported through a pipe, comprising a magnetically inductive flow meter, of which the measuring tube is introduced into the pipe, and a control element which influences the flow of the product and which is designed to be actuated by a drive unit via a mechanically displaceable rod-like actuator.
Devices of this type are used in particular as metering heads for filling containers with predetermined quantities of the fluid product. In this case, the control element is a valve which controls the flow of the product. By means of the magnetically inductive flow meter, it is possible to determine the quantity of product which has passed through the pipe since the opening of the valve. When the measured quantity of product corresponds to the preset quantity, the valve is closed. The use of a magnetically inductive flow meter affords the advantage that no moving parts or constrictions are situated in the flow path of the product. In this way, it is also readily possible thoroughly to clean the plant, including the flow meter, as required in particular for observing food regulations.
Devices of the type in question are known, for example, from DE-OS No. 33 39 274 and from DE-GM No. 83 11 725. In these known devices, the magnetically inductive flow meter is introduced into the pipe at a point situated upstream of the valve and its actuating mechanism in the direction of flow so that these components do not impair the operation of the magnetically inductive flow meter. Accordingly, the magnetically inductive flow meter is situated at a considerable distance from the outlet opening for the product. This can give rise to measurement errors through delayed response or afterflow of the product. In the device known from DE-GM No. 83 11 725, the valve is positioned at the actual outlet opening to prevent afterflow and is actuated by an actuating rod which extends axially through a filling tube forming the end section of the pipe. However, the magnetically inductive flow meter is again arranged in that part of the pipe which precedes the filling tube and, accordingly, is situated at a correspondingly large distance from the outlet opening and the valve.
The application of this known construction principle creates problems of space, particularly in filling plants comprising a relatively large number of metering heads situated closely adjacent one another for simultaneously filling a relatively large number of containers. In this case, each metering head must of course be equipped with its own magnetically inductive flow meter and the accommodation of the necessary number of magnetically inductive flow meters can cause difficulties, particularly in view of the short flow paths required.